耐亚胺培南鲍氏不动杆菌blaOXA基因型检测及同源性分析

Study on blaOXAgenotype and genetic homology of imipenem-resistant Acinetobacter baumannii

目的了解宁夏地区耐亚胺培南鲍氏不动杆菌的耐药性、blaOXA基因型及同源性。方法收集2005年9月-2009年12月从临床感染标本检出耐亚胺培南鲍氏不动杆菌59株,重新传种、鉴定、用K-B法进行药敏试验;PCR扩增blaOXA23、blaOXA24、blaOXA51和blaOXA58基因;脉冲场凝胶电泳(PFGE)分析基因同源性。结果 59株耐亚胺培南鲍氏不动杆菌对阿米卡星的敏感率最高为64.4%,其次是米诺环素33.9%、多西环素32.2%;OXA-23基因阳性44株、OXA-51基因阳性59株,未发现OXA-24和OXA-58型β-内酰胺酶基因;59株耐亚胺培南鲍氏不动杆菌根据PFGE分型分为A、B两型,A1型51株、A2型7株、B型1株为散发型。结论医院感染耐亚胺培南鲍氏不动杆菌同时对其他抗菌药物耐药情况严重,耐药机制可能与携带blaOXA-23基因有关;该院存在克隆传播,提示应加强医院感染监测和处理措施。

OBJECTIVE To investigate the drug resistance, genotype of blaOXA, and genetic homology of irnipenem- resistant Acinetobacter baumannii isolated from Ningxia area. METHODS Totally 59 strains of imipenem-resistant A. baumannii isolated from infectious clinical specimens between Sep 2005 to Dec 2009 were collected, then the retransmission and identification of the strains as well as the drug susceptibility testing were preformed, the blaOXA23, blaOXA24, blaOXA51, and blaOXA58 genes were amplified by PCR, and the genetic homology was analyzed with the use of pulsed field gel electrophoresis （PFGE）. RESULTS The drug susceptibility rate of the 59 strains of imipenem-resistan A. baumannii to amikacin was the highest （64.4%）, followed by the minocycline （33.9%） and doxycycline （32.2%）. There were 44 isolates with OXA-23 gene tested positive and 59 isolates with OXA-51 gene recommended positive, and β-lactamase genes OXA-24 and OXA-58 have not been detected in the strains. The 59 strains of imipenem-resistan A. baumannii were classified into the type A and type B according to the PFGE genotyping, including 51 strains of type A1, 7 strains of type A2, and 1 strain of disseminated type B. CONCLUSION The imipenem-resistant A. baumannii strains are highly resistant to other antibiotics, and the drug resistance mechanism may be associated with their carrying blaOXA-23 gene; the clone strains spread in the hospital, indicating that the monitoring of nosocomial infections and the treatment measures should be strengthened.